Consider the schedule below. Here, R(·) and W(·) stands for 'Read' and Write', respectively. T; represents a transaction, and t; represents the time slot. t2 t3 t4 t5 to t7 ts to T1 R(Y) W(X) T2 R(X) T3 W(Y) R(Z) T4 W(X) R(Y) R(X) T5 W(Y) Figure 2: Schedule of Q5(a). Give the complete precedence graph of this schedule and label the data item(s) for each edge, determine if this is a conflict serializable graph?

Consider the schedule below. Here, R(·) and W(·) stands for 'Read' and Write', respectively. T; represents a transaction, and t; represents the time slot. t2 t3 t4 t5 to t7 ts to T1 R(Y) W(X) T2 R(X) T3 W(Y) R(Z) T4 W(X) R(Y) R(X) T5 W(Y) Figure 2: Schedule of Q5(a). Give the complete precedence graph of this schedule and label the data item(s) for each edge, determine if this is a conflict serializable graph?

Database Systems: Design, Implementation, & Management

11th Edition

ISBN:9781285196145

Author:Steven, Steven Morris, Carlos Coronel, Carlos, Coronel, Carlos; Morris, Carlos Coronel and Steven Morris, Carlos Coronel; Steven Morris, Steven Morris; Carlos Coronel

Publisher:Steven, Steven Morris, Carlos Coronel, Carlos, Coronel, Carlos; Morris, Carlos Coronel and Steven Morris, Carlos Coronel; Steven Morris, Steven Morris; Carlos Coronel

Chapter10: Transaction Management And Concurrency Control

Section: Chapter Questions

Problem 15RQ

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Similar questions

75. ________ allows only committed data to be read and further requires that no other transaction is allowed to update it between two reads of a data item by a transaction. a. Read uncommitted b. Serializable c. Repeatable read d. Read committed
9. When transaction Ti requests a data item currently held by Tj , Ti is allowed to wait only if it has a timestamp smaller than that of Tj (that is, Ti is older than Tj ). Otherwise, Ti is rolled back (dies). This is a. Wait-die b. Wait-wound c. Wound-wait d. Wait
15. A transaction performs on the isolation level of the Read Uncommitted if : a. A dirty read occurs b. Non-repeatable read occurs c. Phantom reads occurs d. All of the above
The first rule in the basic timestamping protocol for concurrency control is: If transaction T asks to read the variable P, check for any younger transaction’s write. If WriteTimestamp(P) > TimeStamp(T), then T is late to read (the value of P it needs is already overwritten, will be inconsistent read) Explain why this rule states that the value of P that this transaction needs is already overwritten.
Please refer to this textbook: “A. Silberschatz, P. B. Galvin and G. Gagne, “Operating System Principles,”7th Edition, John Wiley & Sons Inc., 2006.” And answer the following questions: Question10: The following is not a property of transactions: (a) Permanent: once committed, the results of a transaction are made permanent. (b) Serializable: the result of concurrent transactions must be the same as if they were run in serial order. (c) Indivisible: the transaction appears as an indivisible action. (d) Bounded: a transaction must have an upper bound on the time it takes to complete
Transactions often take a very long time to finish when an optimistic approach to concurrency management is used. Explain.
87. The property of transaction that persists all the crashes is a. Atomicity b. Durability c. Isolation d. All of the mentioned
What are the pros and cons of pessimistic concurrency in relation to optimistic concurrency? What are the pros and cons of explicit transactions in relation to implicit transactions, and vice versa? Support your rationale.
why is it more difficult to find concurrency bugs compared to regular logic errors?
For each of the following isolation levels, give an example of a schedule that respects the specified level of isolation but is not serializable: a. Read uncommitted b. Read committed c. Repeatable read
Explain what is commit message?
Define the microoperations defined for each control word in the blank fields. If more than one microtransaction can be processed at the same time, specify these transactions by separating them with commas.

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